Floating Plug Anti-Leak

ABSTRACT

A roller cone drill bit includes a pressure equalization bore defined within the roller cone drill bit that includes a lubricant chamber portion and an open portion. The drill bit also includes a lubricant passage defined within the drill bit and fluidically coupled to a first end of the lubricant chamber portion. Additionally, the roller cone drill bit includes a floating plug positioned within the pressure equalization bore between the lubricant chamber portion and the open portion. The floating plug is slidable along the pressure equalization bore and configured to seal the lubricant chamber portion from the open portion. Moreover, the roller cone drill bit includes a stop positioned at least partially within the pressure equalization bore or the lubricant passage to restrain the floating plug from sliding into the lubricant passage through the first end of the lubricant chamber portion.

BACKGROUND

Lubricant is used in drill bits for various purposes, among which is to exclude well fluids and debris from interfaces between components of the drill bits that move relative to one another. For example, lubricant may be used between cones of a roller cone bit and journals on which the cones rotate.

Currently, lubricant in a roller cone bit is maintained at a pressure which is substantially equal to the surrounding borehole environment, so that seals which isolate the lubricant from well fluids in the environment do not have to withstand significant pressure differentials in use. However, current roller cone bits may allow for a floating plug to slip from a pressure equalization bore that houses the floating plug into a lubricant passage that houses the lubricant used between the cones of the roller cone bit and the journals on which the cones rotate. This may allow for free flow of annulus fluid and/or mud pumped from the surface through the drill bit to reach bearings in the drill bit, which may reduce bearing life. Additionally, the floating plug may slip into other passages, preventing the flow of grease to the bearing, which may also reduce bearing life.

BRIEF DESCRIPTION OF THE DRAWINGS

These drawings illustrate certain aspects of some examples of the present disclosure and should not be used to limit or define the disclosure.

FIG. 1 is a representative side elevation, partial cross-sectional view of an operational environment for a drilling system, in accordance with one or more embodiments of the disclosure;

FIG. 2 is a representative side view of a drill bit which can embody principles of this disclosure in accordance with one or more embodiments of the disclosure;

FIG. 3 is a representative cross-sectional view of a body of the drill bit in accordance with one or more embodiments of the disclosure;

FIG. 4 is a representative oblique cross-sectional view of an arm of another example of the drill bit;

FIGS. 5-9 are representative cross-sectional views of additional examples of the drill bit;

FIG. 10 is a representative cross-sectional view of a pressure relief valve which may be used in the drill bit, and which can embody principles of this disclosure, in accordance with one or more embodiments of the disclosure;

FIG. 11 is another example of a representative cross-sectional view of the body of the drill bit with a stop;

FIGS. 12A-F are representative cross-sectional views of different stops which may be used in the drill bit in accordance with one or more embodiments of the present disclosure;

FIG. 13 is representative cross-sectional view of a ledge which may be used in the drill bit in accordance with one or more embodiments of the present disclosure; and

FIG. 14A-C are representative cross-sectional views of a floating plug which may be used in the drill bit.

DETAILED DESCRIPTION

This disclosure relates generally to equipment utilized in drilling operations of subterranean wells and, in an example described below, more particularly provides floating plug pressure equalization in drill bits (e.g., roller cone bits). Embodiments of this disclosure may generally relate to a system and method for preventing movement of a floating plug out of a pressure equalization bore in a drill bit. As disclosed below, devices may be employed to prevent the floating plug from ejecting out of the pressure equalization bore and into a fluidly connected lubricant passageway, which may prevent drilling fluid from a wellbore from leaking into a lubricant reservoir that houses a lubricant configured to lubricate portions of the drill bit (e.g., bearings). The lubricant reservoir extends from the floating plug to the bearings. That is, the lubricant reservoir includes the portion of the pressure equalization bore disposed between the floating plug and the lubricant passageway (e.g., a lubricant chamber portion of the pressure equalization bore), as well as the fluidly connected lubricant passageway. Preventing ejection of the floating plug into the lubricant reservoir may allow for longer bearing life by preventing leaks of annulus fluid or mud pumped from the surface from reaching the bearings through the lubricant chamber portion.

FIG. 1 illustrates a side elevation, partial cross-sectional view of an operational environment for a drilling system in accordance with one or more embodiments of the disclosure. It should be noted that while FIG. 1 generally depicts a land-based drilling assembly, those skilled in the art will readily recognize that the principles described herein are equally applicable to subsea drilling operations that employ floating or sea-based platforms and rigs, without departing from the scope of the disclosure. As illustrated, drilling assembly 100 may include a drilling platform 102 that supports a derrick 104 having a traveling stop 106 for raising and lowering a drill string 108. Drill string 108 may include, but is not limited to, drill pipe and coiled tubing, as generally known to those skilled in the art. A kelly 110 may lowered through a rotary table 112 and can be used to transmit rotary motion from the rotary table to drill string 108. A drill bit 114 may be attached to the distal end of drill string 108 and may be driven by a downhole motor and/or via rotation of drill string 108. As drill bit 114 rotates, it penetrates various subterranean formations 116 to form a wellbore 118.

FIG. 2 illustrates an example of drill bit 114 of FIG. 1. As illustrated, drill bit 114 is a roller cone bit having one or more conical-shaped roller cones 200 rotatably secured to one or more corresponding arms 202 extending from a main body 204 of drill bit 114. As illustrated, drill bit 114 (e.g., tri-cone bit) includes three roller cones 200 rotatably secured to three corresponding arms 202. However, the principles of this disclosure may be incorporated into drill bits 114 having any number of conical-shaped roller cones 200. Roller cones 200 may have cutting elements 206 (e.g., teeth or inserts) positioned around an exterior surface 208 (e.g., work surface) of each of roller cones 200. Each of cutting elements 206 may be configured to intermittently engage the various subterranean formations 116 based on an orientation of its corresponding roller or cone 200 with respect to subterranean formation 116 at the bottom of wellbore 118. As drill string 108 rotates, contact between the drill bit 114 and subterranean formation 116 at the bottom of wellbore 118 may cause roller cones 200 to rotate about their respective axes 210. Rotation of roller cones 200 may cause each of cutting elements 206 to rotate into contact with subterranean formation 116 at the bottom of wellbore 118 and apply a compressive force to crush at least a portion of subterranean formation 116. Further, rotation of drill bit 114 may cause cutting element 206 to rotate around a central axis of the drill bit, which may cause cutting element 206 to exert a lateral force while cutting element 206 is in contact with subterranean formation 116 to further crush subterranean formation 116. In examples, a combination of the rotation from roller cones 200 and the rotation from drill bit 114 may cause cutting elements 206 to penetrate the various subterranean formations 116 to form wellbore 118.

FIG. 3 illustrates a cross-sectional view of one of the conical-shaped roller cones 200 rotatably secured to one of the arms 202 of FIG. 2 in accordance with one or more embodiments. Drill bit 114, as characteristic of a roller cone bit, includes a bearing system 300 to rotatably secure the conical-shaped roller cones 200 to the respective arms 202. Bearing system 300 may include a journal-bearing system, a roller-bearing system, a ball-bearing system, or some combination thereof. As illustrated, drill bit 114 includes a journal bearing system 302 to rotatably secure a cone 304 to a corresponding arm 306. Arm 306 may include a journal 308 extending from a distal end 310 of the arm. An outer diameter 312 of journal 308 varies along a central axis 314 of journal 308. For example, a distal end 316 of journal 308 has a smaller outer diameter 312 than other portions of journal 308 to form a thrust flange 318 for supporting axial loads transmitted from cone 304. Further, journal 308 includes a circumferential journal slot 320 formed in an outer surface 322 of journal 308. Circumferential journal slot 320 is configured to at least partially house one or more retaining balls 324. Additionally, cone 304 includes a corresponding circumferential cone slot 326 in an inner surface 348 of cone 304 that is configured to at least partially house the one or more retaining balls 324. As illustrated, retaining balls 324 are positioned between cone 304 and journal 308 to secure cone 304 on journal 308 of arm 306. That is, to restrain axial movement of cone 304 with respect to journal 308.

As illustrated in FIG. 3, a ball retaining plug 328 is configured to hold the one or more retaining balls 324 in place during drilling operations. Ball retaining plug 328 are positioned within a lubricant passage 330 extending from an external surface 332 of arm 306 to circumferential journal slot 320 formed in outer surface 322 of journal 308. Ball retaining plug 328 may be secured within lubricant passage 330 via welding or any other suitable process. A proximal end 334 of ball retaining plug 328 is configured to interface with the one or more retaining balls 324. A distal end 336 of ball retaining plug 328 includes a plug portion 338. Plug portion 338 is configured to form a seal between ball retaining plug 328 and lubricant passage 330. In the illustrated embodiment, an outer diameter 340 of a central portion 342 of ball retaining plug 328 is less than a diameter 344 of lubricant passage 330 such that a lubricant may flow through lubricant passage 330 around at least the central portion 342 of the ball retaining plug 328.

Drill bit 114 includes a lubrication system 346 configured to provide a lubricant (e.g., oil, grease) to bearing system 300 to facilitate low-friction rotation of cone 304 with respect to journal 308. Lubrication system 346 is configured to supply the lubricant to an annular gap 354 formed between the inner surface of cone 304 and the outer surface of journal 308. Lubrication system 346 includes a lubricant reservoir 350, which may include any portion of drill bit 114 sealed from wellbore 118 and configured to house the lubricant. Lubricant reservoir 350 may include lubricant chamber portion 352 of pressure equalization bore 358, lubricant passage 330, and annular gap 354. In the illustrated embodiment, the lubricant is supplied to annular gap 354 from lubricant chamber portion 352 via lubricant passage 330. Moreover, lubrication system 346 includes a floating plug 356 positioned at least partially within a pressure equalization bore 358. Lubricant chamber portion 352 includes a portion of pressure equalization bore 358 disposed between floating plug 356 and the fluidly connected lubricant passage 330. Floating plug 356 is configured to travel axially along pressure equalization bore 358 to ensure that the lubricant is at substantially the same pressure as the downhole environment on an exterior 360 of drill bit 114 (e.g., wellbore 118) during drilling operations. Floating plug 356 seals lubricant chamber portion 352 from an open portion 362 of pressure equalization bore 358 (e.g., a portion of pressure equalization bore 358 exposed to the downhole environment) such that lubricant chamber portion 352 and open portion 362 of pressure equalization bore 358 are isolated from fluid communication with each other.

Drill bit 114 may be manufactured to include pressure equalization bore 358, lubricant passage 330, or some combination thereof. Drill bit 114 may be cast, machined, welded, or otherwise manufactured to include pressure equalization bore 358, lubricant passage 330, or some combination thereof. In some embodiments, pressure equalization bore 358, lubricant passage 330, or some combination thereof, are bored into drill bit 114. Pressure equalization bore 358, lubricant passage 330, or some combination thereof, may be bored into drill bit 114 during manufacturing, at drilling platform 102, or at any suitable stage.

As illustrated, lubrication system 346 further includes seals 364 a,b configured to prevent debris and well fluids from entering annular gap 354 formed radially between cone 304 and journal 308. Seals 364 a,b may also prevent escape of the lubricant via annular gap 354. Seals 364 a,b are received in glands or grooves 366 formed in cone 304. Alternatively, seals 364 a,b may be received in glands or grooves 366 formed in journal 308. Although two seals 364 a,b are depicted in the drawings, any number of seals (including one) may be used in keeping with the scope of this disclosure. Moreover, as cone 304 rotates about journal 308, seals 364 a,b preferably rotate with cone 304 against the outer surface of journal 308. In an alternative example, seals 364 a,b may remain stationary on journal 308 (e.g., seals 364 a,b being positioned in the grooves formed in journal 308), with cone 304 rotating relative to journal 308 and seals 364 a,b.

With continued reference to FIG. 3, floating plug 356 is spherically shaped and may include a full sphere. Floating plug 356 may seal lubricant chamber portion 352 from open portion 362 of pressure equalization bore 358. To form the seal, a circumferential portion 368 of floating plug 356 presses against an inner surface 370 of pressure equalization bore 358. The circumferential portion 368 of floating plug 356 may deform or flatten based at least in part on contact with inner surface 370 of pressure equalization bore 358. For example, floating plug 356 could be made entirely or at least exteriorly of an elastomer or other resilient material, which deforms at least partially when floating plug 356 contacts pressure equalization bore 358 to form the seal. During operations, the spherically shaped floating plug 356 rotates within pressure equalization bore 358 without binding and while maintaining the seal against pressure equalization bore 358. In an alternative example, floating plug 356 may be cylindrically shaped, barrel-shaped, etc. Floating plug 356 may be any shape in keeping with the scope of this disclosure. Further, pressure equalization bore 358 may have other shapes. For example, pressure equalization bore 358 may have a square, triangular, or any other suitable cross-sectional shape. Floating plug 356 may have a shape suitable for use with the cross-sectional shape of pressure equalization bore 358.

In the illustrated embodiment, lubrication system 346 includes a retainer 372 to prevent floating plug 356 from being discharged out of pressure equalization bore 358. A pressure differential between lubricant chamber portion 352 and open portion 362 of pressure equalization bore 358 may cause floating plug 356 to traverse along the length of pressure equalization bore 358 in any direction. For example, the pressure differential may cause floating plug 356 to move towards open portion 362 of pressure equalization bore 358. Open portion 362 of pressure equalization bore 358 includes an opening 374 through an external surface 332 of arm 306 of drill bit 114 to exterior 360 (e.g., an annulus formed in wellbore 118 between drill bit 114 and a wellbore wall 376). Retainer 372 is configured to restrain movement of floating plug 356 proximate opening 374 such that floating plug 356 is not discharged from pressure equalization bore 358 into wellbore 118. Further, retainer 372 include a filter 373 that filters well fluid that enters open portion 362 of pressure equalization bore 358. In an alternative embodiment, open portion 362 of pressure equalization bore 358 may be in fluid communication with an interior 378 of drill bit 114 (e.g., via a passage from retainer 372 to the interior 378). During drilling operations, interior 378 may generally be filled with drilling fluid pumped from a rig mud pump (not illustrated). Retainer 372 may be configured to restrain movement of floating plug 356 proximate the opening 374 such that floating plug 356 is not discharged from pressure equalization bore 358 into interior 378 of drill bit 114. Thus, lubricant chamber portion 352 may be equalized in regard to pressure with either wellbore 118 or interior 378 of drill bit 114. With continued reference to FIG. 3, friction between floating plug 356 and inner surface 370 of pressure equalization bore 358 may cause some variation in the pressure differential between open portion 362 of pressure equalization bore 358 and lubricant chamber portion 352. However, floating plug 356 may move along pressure equalization bore 358 to relieve pressure differentials across floating plug 356 such that lubricant chamber portion 352 may be at least partially equalized with open portion 362 of pressure equalization bore 358, which may be equal to the pressure of either wellbore 118 or interior 378 of drill bit 114.

With pressure at least partially equalized between open portion 362 of pressure equalization bore 358 and lubricant chamber portion 352, pressure across seals 364 a,b may be substantially zero, since seals 364 are exposed to the lubricant on one side and wellbore 118, which shares a pressure with open portion 362 of pressure equalization bore 358, on an opposite side of seals 364. However, a pressure in annular gap 354 between the at least two seals 364 a,b may not be equalized with lubricant chamber portion 352, wellbore 118, or interior 378 of drill bit 114. Thus, a pressure differential may still exist across each seal 364 a,b in the example depicted in FIG. 3. In other examples described below, pressure across each of seals may be substantially equalized, using the principles of this disclosure.

In FIG. 4, another embodiment of arm 306 is representatively illustrated in an oblique cross-sectional view, with cone 304, ball retainer plug 328, and retaining balls 324 removed for clarity. Retainer 372 is positioned within open portion 362 of pressure equalization bore 358. As illustrated, retainer 372 does not include filter 373, but filter 373 may be provided. For example, filter 373 may be positioned within an axial bore 400 of retainer 372. Filter 373 may be configured to filter fluids entering open portion 362 of pressure equalization bore 358 through retainer 372 to prevent debris from entering pressure equalization bore 358. Such debris may hinder movement of floating plug 356 along pressure equalization bore 358, which may cause the pressure differential between lubricant reservoir 350 and wellbore 118 to increase.

Moreover, in the illustrated embodiment, lubrication system 346 includes another passage (e.g., a secondary passage 402) extending from lubricant passage 330 toward distal end 316 of journal 308. Secondary passage 402 may supply lubricant to annular gap 354 between journal 308 and cone 304. Thus, as illustrated in FIG. 4, the lubricant may flow from lubricant chamber portion 352 to annular gap 354 via lubricant passage 330 and secondary passage 402.

As illustrated in FIG. 5, another embodiment of arm 306 is representatively illustrated. Pressure across seal 364 b is equalized using a floating plug 356, similar to the manner in which floating plug 356 is used in FIGS. 2 & 3. Note that a conventional pressure equalization device (such as, a diaphragm or membrane, etc.) is preferably used with the configuration of FIG. 5 for equalization of pressure between lubricant chamber portion 352 and exterior 360 of drill bit 114.

In FIG. 5, floating plug 356 may provide for equalization of pressure across at least seal 364 b, thereby also substantially equalizing pressure across each seal 364 a,b, while also preventing leakage through annular gap 354, even if at least one seal 364 a,b may fail. For example, even if seal 364 a may fail, seal 364 b and floating plug 356 may prevent well fluid from flowing into lubricant chamber portion 352 via annular gap 354 or open portion 362 of pressure equalization bore 358, respectively.

As pressure across seal 364 b is equalized, one side of seal 364 b is exposed to the pressure in lubricant chamber portion 352 (e.g., via lubricant passage 330 or secondary passage 402) and an opposite side of seal 364 b is exposed to annular gap 354. During operations, pressure in lubricant chamber portion 352 is equalized with pressure on exterior 360 of drill bit 114 (e.g., using a conventional pressure equalization device, or using floating plug 356 and pressure equalization bore 358 of FIGS. 2 & 3, etc.) as one side of seal 364 a is exposed to annular gap 354 and an opposite side of seal 364 a is exposed to the pressure on exterior 360 of drill bit 114. Thus, pressure on both sides of each seal 364 a,b may be equalized with pressure on exterior 360 of drill bit 114 and neither seal 364 a,b has a substantial pressure differential across it.

FIG. 6 illustrates another configuration of drill bit 114 in accordance with one or more embodiments. As illustrated, lubricant chamber portion 352 and open portion 362 of pressure equalization bore 358 are extended, thereby providing further available displacement of the floating plug 356. This, in turn, provides more initial volume for lubricant, more volume for thermal expansion of the lubricant, and/or more volume for compression of the lubricant at downhole pressures.

FIG. 7 illustrates another example of drill bit 114 in which floating plug 356 is positioned between lubricant chamber portion 352 and open portion 362 of pressure equalization bore 358 to equalize pressure across seal 364 a. For example, lubricant chamber portion 352 is in fluid communication with annular gap 354 between seals 364 a,b, and open portion 362 of pressure equalization bore 358 is in fluid communication with exterior 360 of drill bit 114.

Lubricant chamber portion 352 is also pressure equalized with exterior 360 of drill bit 114 (e.g., as in the examples of FIGS. 2 and 3 or using a conventional pressure equalization device), the result may be that pressure across each seal 364 a,b is substantially equalized, as illustrated in FIG. 6. Note that, in other examples, pressures exposed to seals 364 a,b may be equalized with pressure in interior of drill bit 114 (for example, by providing fluid communication between open portion 362 of pressure equalization bore 358 and the interior of drill bit 114).

Referring to FIG. 8, another example of drill bit 114 is illustrated. This example is similar in many respects to FIG. 6, but differs at least in that lubrication system 346 includes both floating plug 356 and an additional floating plug (e.g., a second floating plug 800). Second floating plug 800 may be positioned within pressure equalization bore 358pressure equalization bore 358 to equalize pressure between exterior 360 and annular gap 354 between seals 364 a,b.

Referring to FIG. 9, another example of drill bit 114 is representatively illustrated, in which pressure equalization bore 358 extends through arm 306, and floating plug 356 is sealed and reciprocally received in pressure equalization bore 358. Open portion 362 of pressure equalization bore 358 is in fluid communication with exterior 360 of drill bit 114, and lubricant chamber portion 352 is in fluid communication with annular gap 354 between seals 364 a,b. An enlarged bypass chamber 900 is provided at an end of lubricant chamber portion 352 of pressure equalization bore 358, in order to allow well fluid to bypass floating plug 356, for example, in the event that there is excessive loss of lubricant from lubricant chamber portion 352. As lubricant is lost from lubricant chamber portion 352, floating plug 356 displaces toward the bypass chamber 900 (e.g., open portion 362 of pressure equalization bore 358 lengthens, and lubricant chamber portion 352 shortens). Eventually, floating plug 356 may enter the bypass chamber 900, and the well fluid may then flow around floating plug 356. In this manner, pressure across seals 364 a,b may still be equalized, even though floating plug 356 may no longer isolate the lubricant from the well fluid.

FIG. 10 illustrates drill bit 114 in which floating plug 356 may be used as part of a pressure relief valve 1000 in addition to being used to substantially equalize pressure between lubricant chamber portion 352 and exterior 360 of drill bit 114 in accordance with one or more embodiments. Pressure relief valve 1000 includes floating plug 356, a biasing device 1002 (e.g., a spring), and an enlarged dimension or recess 1004 in the bore, which allows fluid to bypass floating plug 356. As illustrated, the pressure relief valve is positioned within open portion 362 of pressure equalization bore 358.

Further, open portion 362 of pressure equalization bore 358 mis in fluid communication with exterior 360 of drill bit 114, and lubricant chamber portion 352 is in fluid communication with other portions of the lubricant reservoir 350. If (for example, due to thermal expansion, etc.) there is excess pressure in lubricant chamber portion 352, the pressure differential across floating plug 356 may displace the plug in a direction toward the biasing device 1002. For example, the pressure differential may displace floating plug 356 such that floating plug 356 contacts the biasing device 1002. The biasing device 1002 may exert a biasing force to counteract the displacement of the floating plug 356. Based on the pressure differential, floating plug 356 may continue to travel along pressure equalization bore 358 against the biasing device 1002 until floating plug 356 has displaced sufficiently (or, until a predetermined pressure differential across floating plug 356 has been exceeded) for lubricant to flow via the enlarged dimension or recess 1004 to exterior 360, thereby relieving the excess pressure in lubricant chamber portion 352. In another example, pressure relief valve 1000 may be incorporated into the configuration of FIG. 9 for equalizing the pressure across seal 364 a. Biasing device 1002 and recess 1004 could, for example, be provided in pressure equalization bore 358 of the FIG. 8 configuration, or of any of the other configurations described above.

FIG. 11 illustrates a stop 1100 positioned within lubricant chamber portion 352 of FIG. 4 in accordance with one or more embodiments. Stop 1100 may also be referred to as a block. During drilling operations, the lubricant (e.g., grease) may be consumed at seals 364 a,b or otherwise ejected. Traditionally, lubricant reservoir 350 may leak (e.g., fail to seal the lubricant from the well fluid) when a certain amount of the lubricant is consumed. For example, as the lubricant is consumed, the pressure differential may cause floating plug 356 to slide and/or move along pressure equalization bore 358 toward a first end 1102 of lubricant chamber portion 352 proximate lubricant passage 330. It may be possible for floating plug 356 to pass through first end 1102 of lubricant chamber portion 352 and move into lubricant passage 330. As set forth above, floating plug 356 is configured to form a seal against pressure equalization bore 358. Thus, floating plug 356 ejecting into lubricant passage 330 removes the seal isolating the lubricant from the well fluid, which causes lubricant reservoir 350 to leak. However, as illustrated, lubrication system 346 includes stop 1100 configured to restrict the movement of floating plug 356 to keep floating plug 356 from ejecting into lubricant passage 330 (e.g., a retaining ball plug hole), a bleed hole, or the like. Therefore, stop 1100 causes floating plug 356 to maintain the seal even when the lubricant (e.g., grease) is depleted or the certain amount of the lubricant is consumed. This may translate to longer bearing life.

Referring now to FIGS. 12A-F, floating plug 356 may interact with stop 1100 in accordance with one or more embodiments. It should be noted that there may be any number of various different types of floating plugs 356, which may be used in conjunction with stop 1100. In one example, floating plug 356 is made entirely of an elastomer sealing material for seal engaging against pressure equalization bore 358 to isolate lubricant chamber portion 352, and other portions of lubricant reservoir 350 (e.g., lubricant passage 330), from open portion 362 of pressure equalization bore 358. However, floating plug 356 may be made of any suitable material. FIGS. 12A-F illustrate various examples of stop 1100. These are merely a few examples of a wide variety of different stops 1100 which may be used, and so it should be clearly understood that the scope of this disclosure is not limited at all to only the specific shapes and types of stops 1100 described herein and depicted and described within this disclosure.

FIG. 12A illustrates stop 1100 as a solid body in accordance with one or more embodiments. Stop 1100 may have a substantially cylindrical shape or any other suitable shape. In the illustrated embodiment, stop 1100 has a cylindrical shape. Stop 1100 is press-fit, slip-fit, or machined within pressure equalization bore 358 to hold stop 1100 in place such that stop 1100 may restrict the movement of floating plug 356 to keep floating plug 356 from ejecting into lubricant passage 330. However, lubricant positioned between floating plug 356 and stop 1100 is configured to flow to annular gap 354 via lubricant passage 330, and the press-fit may prevent flow past stop 1100 along pressure equalization bore 358. Thus, as illustrated, drill bit 114 includes a bypass line 1200 that is connected to pressure equalization bore 358 at one end and lubricant passage 330 at an opposing end. Bypass line 1200 is configured to direct the lubricant positioned between floating plug 356 and stop 1100 to lubricant passage 330.

Alternatively, stop 1100 may not be press-fit in pressure equalization bore 358. Stop 1100 may have a shape configured to permit fluid to flow past stop 1100 along pressure equalization bore 358. An outer diameter 1202 of stop 1100 may be less than a diameter 1204 of pressure equalization bore 358. The lubricant may be configured to flow past stop 1100 through an annulus 1206 formed between stop 1100 and pressure equalization bore 358. However, as stop 1100 is not press fit in pressure equalization bore 358, stop 1100 may slide along pressure equalization bore 358. To restrain stop 1100 (e.g., solid body) from sliding along pressure equalization bore 358, pressure equalization bore 358 may include a ledge or reduced diameter, which may prevent stop 1100 from sliding into lubricant passage 330. In another example, stop 1100 may extend from pressure equalization bore 358 into lubricant passage 330 and to an opposite side wall 1208 of lubricant passage 330 such that contact with opposite side wall 1208 restrains axial movement (e.g., sliding) of stop 1100 in a direction toward lubricant passage 330. Further, in another example, stop 1100 may extend into lubricant passage 330 to a portion of the ball restraining plug such that contact with the ball restraining plug restrains axial movement of stop 1100 in a direction toward lubricant passage 330. Restraining the axial movement of stop 1100 toward lubricant passage 330 may maintain stop 1100 at least partially positioned within pressure equalization bore 358, such that stop 1100 may keep floating plug 356 from ejecting into lubricant passage 330.

FIG. 12B illustrates stop 1100 with a solid body and a cup 1210 for receiving floating plug 356 in accordance with one or more embodiments. Stop 1100 may be press-fit in bore pressure equalization bore 358, and bypass line 1200 (e.g., referring to FIG. 12A) directs the lubricant positioned between floating plug 356 and stop 1100 to lubricant passage 330. Additionally, stop 1100 may have a shape configured to permit fluid (e.g., the lubricant) to flow past stop 1100 along pressure equalization bore 358. That is, the lubricant may flow through the annulus 1206 formed between stop 1100 and pressure equalization bore 358. Moreover, cup 1210 is configured to receive the floating plug 356. Cup 1210 may be any suitable geometry for receiving the floating plug 356. Without limitation, the suitable geometry may be chamfered, rounded, flat, convex, concave, or the like. Additionally, although FIG. 12B illustrates cup 1210 positioned on one side of stop 1100, it should be noted that on the opposite side of stop 1100 may include cup 1210, or any suitable geometry such as chamfered, flat, rounded, convex, concave, and/or the like. To that end, the body of stop 1100 may be any suitable shape such as a cylinder, a sphere, and/or the like.

FIG. 12C further illustrates stop 1100 with a slotted body including slots or grooves 1212 in accordance with one or more embodiments. Slots or grooves 1212 may be evenly spaced, not evenly spaced, strait, helix or any other geometry. It should be noted that the slots or grooves 1212 may not be formed in an exterior surface 1214 of stop 1100 but may traverse through stop 1100 along an axial length 1216 of stop 1100. Additionally, the slots or grooves 1212 may be positioned on an inner surface 370 of pressure equalization bore 358. Lubricant positioned between floating plug 356 and stop 1100 may be configured to flow through the slots 1212 in its path to annular gap 354. Moreover, stop 1100 with the slotted body may be press-fit, or otherwise secured, within pressure equalization bore 358.

FIG. 12D illustrates stop 1100 having an annular body in accordance with one or more embodiments. The annular body of stop 1100 includes a stop bore 1218 extending through the axial length 1216 of stop 1100. It should be noted stop bore 1218 may not be centered within the annular body of stop 1100 and there may be any number of stop bores 1218. The lubricant positioned between floating plug 356 and stop 1100 may be configured to flow through stop bore 1218 in its path to annular gap 354. Moreover, stop 1100 may be press-fit, or otherwise secured, within pressure equalization bore 358. Alternatively, stop 1100 is not press-fit in pressure equalization bore 358. Instead, stop 1100 and/or pressure equalization bore 358 may be machined undersized, and/or formed, in place. Further, as set forth above, a portion of stop 1100 may extend into lubricant passage 330 such that a portion of lubricant passage 330 or the ball restraining plug may restrain axial movement of stop 1100 in a direction toward lubricant passage 330.

FIG. 12E illustrates stop 1100 having the annular body in accordance with one or more embodiments. The annular body of stop 1100 includes stop bore 1218 through the axial length 1216 of stop 1100. Further, stop 1100 includes a pass-through bore 1220 of any geometry. It should be noted that pass-through bore 1220 may not be centered within the annular body of stop 1100 and there may be any number of pass-through bores 1220. The lubricant positioned between floating plug 356 and stop 1100 may be configured to flow through the stop bore 1218 and/or the pass-through bore 1220 in its path to annular gap 354. Moreover, stop 1100 may be press-fit, or otherwise secured, within pressure equalization bore 358.

FIG. 12F illustrates a stop 1222 in lubricant passage 330 configured to prevent stop 1100 from traversing into lubricant passage 330 in accordance with one or more embodiments. As set forth above in FIGS. 12A-12F, each stop 1100 may include press fit, slip fit, or tight fit tolerances, except for a solid body illustrated in FIG. 11A. Further, during operations, stop 1100 functions to prevent floating plug 356 from moving into lubricant passage 330 from lubricant chamber portion 352. Moreover, as discussed below, stop 1100 may work in conjunction with stop 1222 to prevent the movement of floating plug 356 into lubricant passage 330 from lubricant chamber portion 352. For any items above not machined or press fit into lubricant chamber portion 352, the design may accommodate the perpendicular hole (e.g., lubricant passage 330) volume, or pressure equalization bore 358. For example, the length of stop 1100 part may be longer than the diameter of lubricant passage 330 of the inclusion of stop 1222. In another example, the ball retaining plug may allow for a shorter stop 1222 to be used, as the ball retaining plug blocks at least a portion of the passage's 330 cross-section.

Without limitations, stop 1100 and stop 1222 may be keyed for orientation. For example, if a special feature and/or geometry is used on stop 1222 that needs to be oriented toward lubrication chamber 352, then stop 1222 may be keyed to elicit a specified orientation. To that end, stop 1222 may have a feature such as cup 1210 on any surface of stop 1222 to receive floating plug 356. This feature does not have to be cup 1210. It may instead be a flat feature or any other feature, as described above. It should be noted that, as illustrated in FIGS. 12A-12F, stop 1222 may have any of the same features, properties, and/or characteristics of stop 1100. Similar to stop 1100, stop 1222 may also include press fit or tight fit tolerances, unless stop 1222 includes a solid body.

FIG. 13 illustrates the lubrication chamber 352 of pressure equalization bore 358 having a ledge 1300 configured to keep floating plug 356 from ejecting into lubricant passage 330 in accordance with one or more embodiments. Ledge 1300 is configured to restrict movement of floating plug 356, such that stop 1100 may not be needed to keep floating plug 356 from ejecting into lubricant passage 330. Ledge 1300 may be machined into pressure equalization bore 358. In the illustrated embodiment, ledge 1300 includes an annular platform 1302. Ledge 1300 may be formed via a decrease in diameter of pressure equalization bore 358 in a portion of pressure equalization bore 358 proximate lubricant passage 330.Ledge 1300 may not be continuous all the way around lubricant passage 330. Instead, ledge 1300 may extend across at least a portion of pressure equalization bore 358 in a single location (e.g., as a cantilever beam) or a combination of locations (e.g., a 2-legged or 3-legged bridge). Moreover, as illustrated, ledge 1300 is positioned within pressure equalization bore 358. Alternatively, ledge 1300 may be positioned at least partially within lubricant passage 330.

FIG. 14A illustrates floating plug 356 having a cylindrical shape (e.g., a cylindrical floating plug 356) in accordance with one or more embodiments. As set forth above, the differential pressure between lubricant chamber portion 352 and open portion 362 of pressure equalization bore 358 may cause cylindrical floating plug 356 to move toward lubricant passage 330. Without stop 1100, it is possible for cylindrical floating plug 356 to eject into lubricant passage 330, thereby breaking the seal that is configured to isolate the lubricant from the well fluid. However, as illustrated, cylindrical floating plug 356 has an axial length 1400 greater than diameter 344 of lubricant passage 330 such that a portion of cylindrical floating plug 356 remains in pressure equalization bore 358 when cylindrical floating plug 356 is fully extended into lubricant passage 330. That is, when cylindrical floating plug 356 extends into lubricant passage 330 and to opposite side wall 1208 of lubricant passage 330. Contact between opposite side wall 1208 of lubricant passage 330 and an axial end 1402 of cylindrical floating plug 356 restrains cylindrical floating plug 356 from sliding further into lubricant passage 330. A sealing portion 1404 of cylindrical floating plug 356 (e.g., a portion of the plug remaining in pressure equalization bore 358) is configured to maintain the seal that is configured to isolate the lubricant from the well fluid.

FIG. 14B illustrates floating plug 356 with a cylindrical shape and extending into lubricant passage 330 having ball retaining plug 328 positioned therein in accordance with one or more embodiments. Ball retaining plug 328 is configured to restrain the floating plug 356 from sliding further into lubricant passage 330 and/or ejecting into lubricant passage 330. That is, contact between ball retaining plug 328 and axial end 1402 of floating plug 356 restrains floating plug 356 from sliding further into lubricant passage 330.

FIG. 14C illustrates floating plug 356 having a spherical shape and extending into lubricant passage 330 in accordance with one or more embodiments. As illustrated, diameter 1204 of pressure equalization bore 358 is greater than diameter 344 of lubricant passage 330. Further, floating plug 356 has a radius 1420 greater than diameter 344 of lubricant passage 330 such that a portion of floating plug 356 remains in pressure equalization bore 358 when floating plug 356 is fully extended into lubricant passage 330. That is, when floating plug 356 extends into lubricant passage 330 and to opposite side wall 1208 of lubricant passage 330. Contact between opposite side wall 1208 of lubricant passage 330 and circumferential portion 368 of floating plug 356 may restrain floating plug 356 from sliding further into lubricant passage 330. Moreover, the portion of floating plug 356 remaining in pressure equalization bore 358 when floating plug 356 is fully extended into lubricant passage 330 is configured to maintain the seal that is configured to isolate the lubricant from the well fluid.

In accordance with present embodiments, all floating plugs 356 and stops 1100 in FIGS. 12A-14C may be used in any combination. For example, cup 1210 may be included with stop 1100 having the annular body. Moreover, any version or combinations of floating plug 356 or stop 1100 may be symmetric or a-symmetric. For example, stop 1100 may have a first slot 1212 extending along a first side of stop 1100 and a second slot 1212 extending along an opposing second side of stop 1100. In another example, stop 1100 may have a single slot 1212 extending along the first side of stop 1100. Moreover, the material used for floating plug 356 or stop 1100 may be of any material that may maintain structural integrity in the applied environment considering such things as temperature, corrosion, fluid compatibility, etc. For example, a steel or plastic may be used so long as it will not fail at temperature and is compatible with the lubricant (e.g., grease).

In accordance with present embodiments, all features of the stops 1222 in FIG. 12F may be used in any combination with the features described for floating plug 356 or stop 1100. For example, cup 1210 may be included with stop 1222. Further, as set forth above, any version or combinations of stop 1222, the floating plug 356, and stop 1100 may be symmetric or a-symmetric. Moreover, the material used for stop 1222 may be of any material that may maintain structural integrity in the applied environment considering conditions such as temperature, corrosion, fluid compatibility, etc. For example, a steel or plastic may be used so long as it will not fail at temperature and is compatible with the grease.

The preceding description provides various examples of the systems and methods of use disclosed herein which may contain different method steps and alternative combinations of components. Among other things, improvements over current wellbore drilling operations include preventing the floating plug from slip into other portions of the lubricant reservoir (e.g., the passage), thereby maintaining the seal isolating the lubricant reservoir from the well fluid, which may extend bearing life of the bearing system of the roller cone bit.

Statement 1. A roller cone drill bit may comprise a pressure equalization bore defined within the roller cone drill bit that includes a lubricant chamber portion and an open portion; a lubricant passage defined within the drill bit and fluidically coupled to a first end of the lubricant chamber portion; a floating plug positioned within the pressure equalization bore between the lubricant chamber portion and the open portion, wherein the floating plug is slidable along the pressure equalization bore and seals the lubricant chamber portion from the open portion; and a stop positioned at least partially within the pressure equalization bore or the lubricant passage, wherein the stop restrains the floating plug from sliding into the lubricant passage through the first end of the lubricant chamber portion.

Statement 2. The drill bit of statement 1, further comprising a bypass line that is connected to the pressure equalization bore at one end and the lubricant passage at an opposing end of the bypass line.

Statement 3. The drill bit of statement 1 or statement 2, wherein the stop is a ledge machined into the pressure equalization bore.

Statement 4. The drill bit of statement 1 or statement 2, wherein the stop is a solid body.

Statement 5. The drill bit of any proceeding statement, wherein the stop further includes a cup configured to receive the floating plug.

Statement 6. The drill bit of any proceeding statement, wherein the stop is chamfered, flat, rounded, convex, concave, or any combination thereof.

Statement 7. The drill bit of any of statements 1, 2, 5, or 6 wherein the stop further includes an annular body having a stop bore extending axially through the stop.

Statement 8. The drill bit of any of statements 1, 2, or 5-7, wherein the stop further includes a pass-through bore.

Statement 9. The drill bit of any of statements 1, 2, or 5-8, wherein the stop is press-fit into the lubricant chamber portion.

Statement 10. The drill bit of any of statements 1-3, 5, or 6, wherein the stop is machined into the lubricant chamber portion.

Statement 11. The drill bit of any proceeding statement, wherein the stop further includes a slotted body.

Statement 12. The drill bit of any proceeding statement, wherein at least a part of the lubricant chamber portion has a diameter that is smaller than the floating plug.

Statement 13. A method for forming a lubricant reservoir may comprise manufacturing a drill bit with a pressure equalization bore fluidically coupled to a lubricant passage and the lubricant passage fluidically coupled to one or more bearings; positioning a stop at least partially within the lubricant passage or the pressure equalization bore of the drill bit, wherein the lubricant passage is fluidically coupled to a first end of a lubricant chamber portion of the pressure equalization bore; positioning a floating plug within the pressure equalization bore between the lubricant chamber portion and an open portion of the pressure equalization bore, and wherein the floating plug is slidable along the pressure equalization bore and seals the lubricant chamber portion from the open portion; and filling the lubricant reservoir with a lubricant, the lubricant reservoir extending from the floating plug in the lubricant chamber portion of the pressure equalization bore, through the lubricant passage, and to the one or more bearings.

Statement 14. The method of statement 13, further comprising boring out the drill bit to form the pressure equalization bore.

Statement 15. The method of statement 13, further comprising casting the drill bit to form the pressure equalization bore and the lubricant passage.

Statement 16. The method of any of statements 13-15, wherein the pressure equalization bore includes a bypass line that is connected to the pressure equalization bore at one end and to the lubricant passage at an opposing end of the bypass line.

Statement 17. The method of any of statements 13-16, wherein the stop includes a slotted body.

Statement 18. The method of any of statements 13-17, wherein the stop is a ledge machined into the pressure equalization bore.

Statement 19. The method of any of statements 13-17, wherein the stop is a solid body.

Statement 20. The method of any of statements 13-19, wherein the stop is chamfered, flat, rounded, convex, concave, or any combination thereof.

It should be understood that, although individual examples may be discussed herein, the present disclosure covers all combinations of the disclosed examples, including, without limitation, the different component combinations, method step combinations, and properties of the system. It should be understood that the compositions and methods are described in terms of “comprising,” “containing,” or “including” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components and steps. Moreover, the indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the element that it introduces.

For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. Additionally, whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range are specifically disclosed. In particular, every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values even if not explicitly recited. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited.

Therefore, the present examples are well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular examples disclosed above are illustrative only, and may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Although individual examples are discussed, the disclosure covers all combinations of all of the examples. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. It is therefore evident that the particular illustrative examples disclosed above may be altered or modified and all such variations are considered within the scope and spirit of those examples. If there is any conflict in the usages of a word or term in this specification and one or more patent(s) or other documents that may be incorporated herein by reference, the definitions that are consistent with this specification should be adopted. 

What is claimed is:
 1. A roller cone drill bit comprising: a pressure equalization bore defined within the roller cone drill bit that includes a lubricant chamber portion and an open portion; a lubricant passage defined within the drill bit and fluidically coupled to a first end of the lubricant chamber portion; a floating plug positioned within the pressure equalization bore between the lubricant chamber portion and the open portion, wherein the floating plug is slidable along the pressure equalization bore and seals the lubricant chamber portion from the open portion; and a stop positioned at least partially within the pressure equalization bore or the lubricant passage, wherein the stop restrains the floating plug from sliding into the lubricant passage through the first end of the lubricant chamber portion.
 2. The drill bit of claim 1, further comprising a bypass line that is connected to the pressure equalization bore at one end and the lubricant passage at an opposing end of the bypass line.
 3. The drill bit of claim 1, wherein the stop is a ledge machined into the pressure equalization bore.
 4. The drill bit of claim 1, wherein the stop is a solid body.
 5. The drill bit of claim 4, wherein the stop further includes a cup to receive the floating plug.
 6. The drill bit of claim 4, wherein the stop is chamfered, flat, rounded, convex, concave, or any combination thereof.
 7. The drill bit of claim 1, wherein the stop further includes an annular body having a stop bore extending axially through the stop.
 8. The drill bit of claim 7, wherein the stop further includes a pass-through bore.
 9. The drill bit of claim 8, wherein the stop is press-fit into the lubricant chamber portion.
 10. The drill bit of claim 1, wherein the stop is machined into the lubricant chamber portion.
 11. The drill bit of claim 1, wherein the stop further includes a slotted body.
 12. The drill bit of claim 1, wherein at least a part of the lubricant chamber portion has a diameter that is smaller than the floating plug.
 13. A method for forming a lubricant reservoir comprising: manufacturing a drill bit with a pressure equalization bore fluidically coupled to a lubricant passage and the lubricant passage fluidically coupled to one or more bearings; positioning a stop at least partially within the lubricant passage or the pressure equalization bore of the drill bit, wherein the lubricant passage is fluidically coupled to a first end of a lubricant chamber portion of the pressure equalization bore; positioning a floating plug within the pressure equalization bore between the lubricant chamber portion and an open portion of the pressure equalization bore, and wherein the floating plug is slidable along the pressure equalization bore and seals the lubricant chamber portion from the open portion; and filling the lubricant reservoir with a lubricant, the lubricant reservoir extending from the floating plug in the lubricant chamber portion of the pressure equalization bore, through the lubricant passage, and to the one or more bearings.
 14. The method of claim 13, further comprising boring out the drill bit to form the pressure equalization bore.
 15. The method of claim 13, further comprising casting the drill bit to form the pressure equalization bore and the lubricant passage.
 16. The method of claim 13, wherein the pressure equalization bore includes a bypass line that is connected to the pressure equalization bore at one end and to the lubricant passage at an opposing end of the bypass line.
 17. The method of claim 13, wherein the stop includes a slotted body.
 18. The method of claim 13, wherein the stop is a ledge machined into the pressure equalization bore.
 19. The method of claim 13, wherein the stop is a solid body.
 20. The method of claim 13, wherein the stop is chamfered, flat, rounded, convex, concave, or any combination thereof. 